At a loss, need advice.

My nephew is 8 years old & as far as 8 year olds go. He's pretty normal. Innocent nature and so on,. Mostly hangs around with girls in school and out. Last year we had an incident occur where he came home from playing with his friends and his penis was bleeding, to which after some discussion his mum was told that it was the girls that had been touching him. Mother went the right paths to get to bottom of it, speak to parents. Hear full stories etc & agreed to all stay away from one another in the future.Recently he's had a sudden outburst of honesty and is confessing things he's been holding in for the last year or so. With all this confessing etc coming to surface, we've now been informed that another incident has occured with the same girl, being that they were playing at the girls house where they made a den/fort in the living room whilst the girl's parents were in the kitchen. Now the way he has described the incident they were in the den & they have both ended up with their trousers down, they kissed & my nephew beleive's that he had sex with her. (But from what he's described to his mother he hasn't) He's been very emotional & extreamly upset over all of this, which is to be expected to of kept this a secret for so long. Mother has been into school to speak to the head teacher as an attempt to find some kind of neutral ground to discuss this out with the parents, possibly some kind of legal standing person & get to the bottom of it all. But basically been told school are unable to assist with the situation and she has to go about it all herself with the girl's parents etc.The mother has 3 other kids, been a mum for 13 years and never came across this kind of situation before. We really don't know what to do, where to turn to, what to say to him about it all. Everything basically. Obviously isn't a day-to-day situation. Any help/advice would be greatly appreciated. via /r/Parenting http://ift.tt/2DKATdr